I have a system where I send an Ajax command, which returns a script block with a function in it. After this data is correctly inserted in the DIV, I want to be able to call this function to perform the required actions.
Is this possible?
This question is related to
javascript
ajax
function
If your AJAX script takes more than a couple milliseconds to run, eval() will always run ahead and evaluate the empty response element before AJAX populates it with the script you're trying to execute.
Rather than mucking around with timing and eval(), here is a pretty simple workaround that should work in most situations and is probably a bit more secure. Using eval() is generally frowned upon because the characters being evaluated as code can easily be manipulated client-side.
In this example, I want to attach a dynamic autocomplete list from the jquery-ui library to an AJAX element AFTER the element has been added to the page. Easy, right?
start.php
<!DOCTYPE html>
<html>
<head>
<title>Demo</title>
<!-- these libraries are for the autocomplete() function -->
<link rel="stylesheet" type="text/css" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.11.4/themes/ui-lightness/jquery-ui.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.11.4/jquery-ui.min.js"></script>
<script type="text/javascript">
<!--
// this is the ajax call
function editDemoText(ElementID,initialValue) {
try { ajaxRequest = new XMLHttpRequest();
} catch (e) {
try { ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try { ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {
return false;
}}}
ajaxRequest.onreadystatechange = function() {
if ( ajaxRequest.readyState == 4 ) {
var ajaxDisplay = document.getElementById('responseDiv');
ajaxDisplay.innerHTML = ajaxRequest.responseText;
}
}
var queryString = "?ElementID="+ElementID+"&initialValue="+initialValue;
ajaxRequest.open("GET", "ajaxRequest.php"+queryString, true);
ajaxRequest.send(null);
}
// this is the function we wanted to call in AJAX,
// but we put it here instead with an argument (ElementID)
function AttachAutocomplete(ElementID) {
// this list is static, but can easily be pulled in from
// a database using PHP. That would look something like this:
/*
* $list = "";
* $r = mysqli_query($mysqli_link, "SELECT element FROM table");
* while ( $row = mysqli_fetch_array($r) ) {
* $list .= "\".str_replace('"','\"',$row['element'])."\",";
* }
* $list = rtrim($list,",");
*/
var availableIDs = ["Demo1","Demo2","Demo3","Demo4"];
$("#"+ElementID).autocomplete({ source: availableIDs });
}
//-->
</script>
</head>
<body>
<!-- this is where the AJAX response sneaks in after DOM is loaded -->
<!-- we're using an onclick event to trigger the initial AJAX call -->
<div id="responseDiv"><a href="javascript:void(0);" onclick="editDemoText('EditableText','I am editable!');">I am editable!</a></div>
</body>
</html>
ajaxRequest.php
<?php
// for this application, onfocus works well because we wouldn't really
// need the autocomplete populated until the user begins typing
echo "<input type=\"text\" id=\"".$_GET['ElementID']."\" onfocus=\"AttachAutocomplete('".$_GET['ElementID']."');\" value=\"".$_GET['initialValue']."\" />\n";
?>
My usual ajax calling function:
function xhr_new(targetId, url, busyMsg, finishCB)
{
var xhr;
if(busyMsg !== undefined)
document.getElementById(targetId).innerHTML = busyMsg;
try { xhr = new ActiveXObject('Msxml2.XMLHTTP'); }
catch(e)
{
try { xhr = new ActiveXObject('Microsoft.XMLHTTP'); }
catch(e2)
{
try { xhr = new XMLHttpRequest(); }
catch(e3) { xhr = false; }
}
}
xhr.onreadystatechange = function()
{
if(xhr.readyState == 4)
{
if(xhr.status == 200)
{
var target = document.getElementById(targetId)
target.innerHTML = xhr.responseText;
var scriptElements = target.getElementsByTagName("script");
var i;
for(i = 0; i < scriptElements.length; i++)
eval(scriptElements[i].innerHTML);
if(finishCB !== undefined)
finishCB();
}
else
document.getElementById(targetId).innerHTML = 'Error code: ' + xhr.status;
}
};
xhr.open('GET', url, true);
xhr.send(null);
// return xhr;
}
Some explanation:
targetId is an (usually div) element ID where the ajax call result text will goes.
url is the ajax call url.
busyMsg will be the temporary text in the target element.
finishCB will be called when the ajax transaction finished successfully.
As you see in the xhr.onreadystatechange = function() {...} all of the <script> elements will be collected from the ajax response and will be run one by one. It appears to work very well for me. The two last parameter is optional.
I would like to add that there's an eval function in jQuery allowing you to eval the code globally which should get you rid of any contextual problems. The function is called globalEval() and it worked great for my purposes. Its documentation can be found here.
This is the example code provided by the jQuery API documentation:
function test()
{
jQuery.globalEval("var newVar = true;")
}
test();
// newVar === true
This function is extremely useful when it comes to loading external scripts dynamically which you apparently were trying to do.
This does not sound like a good idea.
You should abstract out the function to include in the rest of your JavaScript code from the data returned by Ajax methods.
For what it's worth, though, (and I don't understand why you're inserting a script block in a div?) even inline script methods written in a script block will be accessible.
This code work as well, instead eval the html i'm going to append the script to the head
function RunJS(objID) {
//alert(http_request.responseText);
var c="";
var ob = document.getElementById(objID).getElementsByTagName("script");
for (var i=0; i < ob.length - 1; i++) {
if (ob[i + 1].text != null)
c+=ob[i + 1].text;
}
var s = document.createElement("script");
s.type = "text/javascript";
s.text = c;
document.getElementsByTagName("head")[0].appendChild(s);
}
My usual ajax calling function:
function xhr_new(targetId, url, busyMsg, finishCB)
{
var xhr;
if(busyMsg !== undefined)
document.getElementById(targetId).innerHTML = busyMsg;
try { xhr = new ActiveXObject('Msxml2.XMLHTTP'); }
catch(e)
{
try { xhr = new ActiveXObject('Microsoft.XMLHTTP'); }
catch(e2)
{
try { xhr = new XMLHttpRequest(); }
catch(e3) { xhr = false; }
}
}
xhr.onreadystatechange = function()
{
if(xhr.readyState == 4)
{
if(xhr.status == 200)
{
var target = document.getElementById(targetId)
target.innerHTML = xhr.responseText;
var scriptElements = target.getElementsByTagName("script");
var i;
for(i = 0; i < scriptElements.length; i++)
eval(scriptElements[i].innerHTML);
if(finishCB !== undefined)
finishCB();
}
else
document.getElementById(targetId).innerHTML = 'Error code: ' + xhr.status;
}
};
xhr.open('GET', url, true);
xhr.send(null);
// return xhr;
}
Some explanation:
targetId is an (usually div) element ID where the ajax call result text will goes.
url is the ajax call url.
busyMsg will be the temporary text in the target element.
finishCB will be called when the ajax transaction finished successfully.
As you see in the xhr.onreadystatechange = function() {...} all of the <script> elements will be collected from the ajax response and will be run one by one. It appears to work very well for me. The two last parameter is optional.
Just remember if you create a function the way below through ajax...
function foo()
{
console.log('foo');
}
...and execute it via eval, you'll probably get a context problem. Take this as your callback function:
function callback(result)
{
responseDiv = document.getElementById('responseDiv');
responseDiv.innerHTML = result;
scripts = responseDiv.getElementsByTagName('script');
eval(scripts[0]);
}
You'll be declaring a function inside a function, so this new function will be accessible only on that scope.
If you want to create a global function in this scenario, you could declare it this way:
window.foo = function ()
{
console.log('foo');
};
But, I also think you shouldn't be doing this...
Sorry for any mistake here...
This code work as well, instead eval the html i'm going to append the script to the head
function RunJS(objID) {
//alert(http_request.responseText);
var c="";
var ob = document.getElementById(objID).getElementsByTagName("script");
for (var i=0; i < ob.length - 1; i++) {
if (ob[i + 1].text != null)
c+=ob[i + 1].text;
}
var s = document.createElement("script");
s.type = "text/javascript";
s.text = c;
document.getElementsByTagName("head")[0].appendChild(s);
}
That seems a rather weird design for your code - it generally makes more sense to have your functions called directly from a .js file, and then only retrieve data with the Ajax call.
However, I believe it should work by calling eval() on the response - provided it is syntactically correct JavaScript code.
I solved this today by putting my JavaScript at the bottom of the response HTML.
I had an AJAX request that returned a bunch of HTML that was displayed in an overlay. I needed to attach a click event to a button in the returned response HTML/overlay. On a normal page, I would wrap my JavaScript in a "window.onload" or "$(document).ready" so that it would attach the event handler to the DOM object after the DOM for the new overlay had been rendered, but because this was an AJAX response and not a new page load, that event never happened, the browser never executed my JavaScript, my event handler never got attached to the DOM element, and my new piece of functionality didn't work. Again, I solved my "executing JavaScript in an AJAX response problem" by not using "$(document).ready" in the head of the document, but by placing my JavaScript at the end of the document and having it run after the HTML/DOM had been rendered.
That seems a rather weird design for your code - it generally makes more sense to have your functions called directly from a .js file, and then only retrieve data with the Ajax call.
However, I believe it should work by calling eval() on the response - provided it is syntactically correct JavaScript code.
I've tested this and it works. What's the problem? Just put the new function inside your javascript element and then call it. It will work.
This does not sound like a good idea.
You should abstract out the function to include in the rest of your JavaScript code from the data returned by Ajax methods.
For what it's worth, though, (and I don't understand why you're inserting a script block in a div?) even inline script methods written in a script block will be accessible.
I solved this today by putting my JavaScript at the bottom of the response HTML.
I had an AJAX request that returned a bunch of HTML that was displayed in an overlay. I needed to attach a click event to a button in the returned response HTML/overlay. On a normal page, I would wrap my JavaScript in a "window.onload" or "$(document).ready" so that it would attach the event handler to the DOM object after the DOM for the new overlay had been rendered, but because this was an AJAX response and not a new page load, that event never happened, the browser never executed my JavaScript, my event handler never got attached to the DOM element, and my new piece of functionality didn't work. Again, I solved my "executing JavaScript in an AJAX response problem" by not using "$(document).ready" in the head of the document, but by placing my JavaScript at the end of the document and having it run after the HTML/DOM had been rendered.
PHP side code Name of file class.sendCode.php
<?php
class sendCode{
function __construct($dateini,$datefin) {
echo $this->printCode($dateini,$datefin);
}
function printCode($dateini,$datefin){
$code =" alert ('code Coming from AJAX {$this->dateini} and {$this->datefin}');";
//Insert all the code you want to execute,
//only javascript or Jquery code , dont incluce <script> tags
return $code ;
}
}
new sendCode($_POST['dateini'],$_POST['datefin']);
Now from your Html page you must trigger the ajax function to send the data.
.... <script src="http://code.jquery.com/jquery-1.9.1.js"></script> ....
Date begin: <input type="text" id="startdate"><br>
Date end : <input type="text" id="enddate"><br>
<input type="button" value="validate'" onclick="triggerAjax()"/>
Now at our local script.js we will define the ajax
function triggerAjax() {
$.ajax({
type: "POST",
url: 'class.sendCode.php',
dataType: "HTML",
data : {
dateini : $('#startdate').val(),
datefin : $('#enddate').val()},
success: function(data){
$.globalEval(data);
// here is where the magic is made by executing the data that comes from
// the php class. That is our javascript code to be executed
}
});
}
Federico Zancan's answer is correct but you don't have to give your script an ID and eval all your script. Just eval your function name and it can be called.
To achieve this in our project, we wrote a proxy function to call the function returned inside the Ajax response.
function FunctionProxy(functionName){
var func = eval(functionName);
func();
}
Note: eval() can be easily misused, let say that the request is intercepted by a third party and sends you not trusted code. Then with eval() you would be running this not trusted code. Refer here for the dangers of eval().
Inside the returned HTML/Ajax/JavaScript file, you will have a JavaScript tag. Give it an ID, like runscript. It's uncommon to add an id to these tags, but it's needed to reference it specifically.
<script type="text/javascript" id="runscript">
alert("running from main");
</script>
In the main window, then call the eval function by evaluating only that NEW block of JavaScript code (in this case, it's called runscript):
eval(document.getElementById("runscript").innerHTML);
And it works, at least in Internet Explorer 9 and Google Chrome.
It is fully possible, and there are even some fairly legitimate use cases for this. Using the Prototype framework it's done as follows.
new Ajax.Updater('items', '/items.url', {
parameters: { evalJS: true}
});
See documentation of the Ajax updater. The options are in the common options set. As usual, there are some caveats about where "this" points to, so read the fine print.
The JavaScript code will be evaluated upon load. If the content contains function myFunc(),
you could really just say myFunc() afterwards. Maybe as follows.
if (window["myFunc"])
myFunc()
This checks if the function exists. Maybe someone has a better cross-browser way of doing that which works in Internet Explorer 6.
Federico Zancan's answer is correct but you don't have to give your script an ID and eval all your script. Just eval your function name and it can be called.
To achieve this in our project, we wrote a proxy function to call the function returned inside the Ajax response.
function FunctionProxy(functionName){
var func = eval(functionName);
func();
}
I've tested this and it works. What's the problem? Just put the new function inside your javascript element and then call it. It will work.
With jQuery I would do it using getScript
I tried all the techniques offered here but finally the way that worked was simply to put the JavaScript function inside the page / file where it is supposed to happen and call it from the response part of the Ajax simply as a function:
...
}, function(data) {
afterOrder();
}
This Worked on the first attempt, so I decided to share.
I would like to add that there's an eval function in jQuery allowing you to eval the code globally which should get you rid of any contextual problems. The function is called globalEval() and it worked great for my purposes. Its documentation can be found here.
This is the example code provided by the jQuery API documentation:
function test()
{
jQuery.globalEval("var newVar = true;")
}
test();
// newVar === true
This function is extremely useful when it comes to loading external scripts dynamically which you apparently were trying to do.
I tried all the techniques offered here but finally the way that worked was simply to put the JavaScript function inside the page / file where it is supposed to happen and call it from the response part of the Ajax simply as a function:
...
}, function(data) {
afterOrder();
}
This Worked on the first attempt, so I decided to share.
It is fully possible, and there are even some fairly legitimate use cases for this. Using the Prototype framework it's done as follows.
new Ajax.Updater('items', '/items.url', {
parameters: { evalJS: true}
});
See documentation of the Ajax updater. The options are in the common options set. As usual, there are some caveats about where "this" points to, so read the fine print.
The JavaScript code will be evaluated upon load. If the content contains function myFunc(),
you could really just say myFunc() afterwards. Maybe as follows.
if (window["myFunc"])
myFunc()
This checks if the function exists. Maybe someone has a better cross-browser way of doing that which works in Internet Explorer 6.
This does not sound like a good idea.
You should abstract out the function to include in the rest of your JavaScript code from the data returned by Ajax methods.
For what it's worth, though, (and I don't understand why you're inserting a script block in a div?) even inline script methods written in a script block will be accessible.
It is fully possible, and there are even some fairly legitimate use cases for this. Using the Prototype framework it's done as follows.
new Ajax.Updater('items', '/items.url', {
parameters: { evalJS: true}
});
See documentation of the Ajax updater. The options are in the common options set. As usual, there are some caveats about where "this" points to, so read the fine print.
The JavaScript code will be evaluated upon load. If the content contains function myFunc(),
you could really just say myFunc() afterwards. Maybe as follows.
if (window["myFunc"])
myFunc()
This checks if the function exists. Maybe someone has a better cross-browser way of doing that which works in Internet Explorer 6.
This does not sound like a good idea.
You should abstract out the function to include in the rest of your JavaScript code from the data returned by Ajax methods.
For what it's worth, though, (and I don't understand why you're inserting a script block in a div?) even inline script methods written in a script block will be accessible.
If your AJAX script takes more than a couple milliseconds to run, eval() will always run ahead and evaluate the empty response element before AJAX populates it with the script you're trying to execute.
Rather than mucking around with timing and eval(), here is a pretty simple workaround that should work in most situations and is probably a bit more secure. Using eval() is generally frowned upon because the characters being evaluated as code can easily be manipulated client-side.
In this example, I want to attach a dynamic autocomplete list from the jquery-ui library to an AJAX element AFTER the element has been added to the page. Easy, right?
start.php
<!DOCTYPE html>
<html>
<head>
<title>Demo</title>
<!-- these libraries are for the autocomplete() function -->
<link rel="stylesheet" type="text/css" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.11.4/themes/ui-lightness/jquery-ui.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.11.4/jquery-ui.min.js"></script>
<script type="text/javascript">
<!--
// this is the ajax call
function editDemoText(ElementID,initialValue) {
try { ajaxRequest = new XMLHttpRequest();
} catch (e) {
try { ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try { ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {
return false;
}}}
ajaxRequest.onreadystatechange = function() {
if ( ajaxRequest.readyState == 4 ) {
var ajaxDisplay = document.getElementById('responseDiv');
ajaxDisplay.innerHTML = ajaxRequest.responseText;
}
}
var queryString = "?ElementID="+ElementID+"&initialValue="+initialValue;
ajaxRequest.open("GET", "ajaxRequest.php"+queryString, true);
ajaxRequest.send(null);
}
// this is the function we wanted to call in AJAX,
// but we put it here instead with an argument (ElementID)
function AttachAutocomplete(ElementID) {
// this list is static, but can easily be pulled in from
// a database using PHP. That would look something like this:
/*
* $list = "";
* $r = mysqli_query($mysqli_link, "SELECT element FROM table");
* while ( $row = mysqli_fetch_array($r) ) {
* $list .= "\".str_replace('"','\"',$row['element'])."\",";
* }
* $list = rtrim($list,",");
*/
var availableIDs = ["Demo1","Demo2","Demo3","Demo4"];
$("#"+ElementID).autocomplete({ source: availableIDs });
}
//-->
</script>
</head>
<body>
<!-- this is where the AJAX response sneaks in after DOM is loaded -->
<!-- we're using an onclick event to trigger the initial AJAX call -->
<div id="responseDiv"><a href="javascript:void(0);" onclick="editDemoText('EditableText','I am editable!');">I am editable!</a></div>
</body>
</html>
ajaxRequest.php
<?php
// for this application, onfocus works well because we wouldn't really
// need the autocomplete populated until the user begins typing
echo "<input type=\"text\" id=\"".$_GET['ElementID']."\" onfocus=\"AttachAutocomplete('".$_GET['ElementID']."');\" value=\"".$_GET['initialValue']."\" />\n";
?>
A checklist for doing such a thing:
func_name = function() {...}Better still, use frameworks which handles it like in Prototype. You have Ajax.updater.
PHP side code Name of file class.sendCode.php
<?php
class sendCode{
function __construct($dateini,$datefin) {
echo $this->printCode($dateini,$datefin);
}
function printCode($dateini,$datefin){
$code =" alert ('code Coming from AJAX {$this->dateini} and {$this->datefin}');";
//Insert all the code you want to execute,
//only javascript or Jquery code , dont incluce <script> tags
return $code ;
}
}
new sendCode($_POST['dateini'],$_POST['datefin']);
Now from your Html page you must trigger the ajax function to send the data.
.... <script src="http://code.jquery.com/jquery-1.9.1.js"></script> ....
Date begin: <input type="text" id="startdate"><br>
Date end : <input type="text" id="enddate"><br>
<input type="button" value="validate'" onclick="triggerAjax()"/>
Now at our local script.js we will define the ajax
function triggerAjax() {
$.ajax({
type: "POST",
url: 'class.sendCode.php',
dataType: "HTML",
data : {
dateini : $('#startdate').val(),
datefin : $('#enddate').val()},
success: function(data){
$.globalEval(data);
// here is where the magic is made by executing the data that comes from
// the php class. That is our javascript code to be executed
}
});
}
Note: eval() can be easily misused, let say that the request is intercepted by a third party and sends you not trusted code. Then with eval() you would be running this not trusted code. Refer here for the dangers of eval().
Inside the returned HTML/Ajax/JavaScript file, you will have a JavaScript tag. Give it an ID, like runscript. It's uncommon to add an id to these tags, but it's needed to reference it specifically.
<script type="text/javascript" id="runscript">
alert("running from main");
</script>
In the main window, then call the eval function by evaluating only that NEW block of JavaScript code (in this case, it's called runscript):
eval(document.getElementById("runscript").innerHTML);
And it works, at least in Internet Explorer 9 and Google Chrome.
It is fully possible, and there are even some fairly legitimate use cases for this. Using the Prototype framework it's done as follows.
new Ajax.Updater('items', '/items.url', {
parameters: { evalJS: true}
});
See documentation of the Ajax updater. The options are in the common options set. As usual, there are some caveats about where "this" points to, so read the fine print.
The JavaScript code will be evaluated upon load. If the content contains function myFunc(),
you could really just say myFunc() afterwards. Maybe as follows.
if (window["myFunc"])
myFunc()
This checks if the function exists. Maybe someone has a better cross-browser way of doing that which works in Internet Explorer 6.
With jQuery I would do it using getScript
A checklist for doing such a thing:
func_name = function() {...}Better still, use frameworks which handles it like in Prototype. You have Ajax.updater.
That seems a rather weird design for your code - it generally makes more sense to have your functions called directly from a .js file, and then only retrieve data with the Ajax call.
However, I believe it should work by calling eval() on the response - provided it is syntactically correct JavaScript code.
With jQuery I would do it using getScript
That seems a rather weird design for your code - it generally makes more sense to have your functions called directly from a .js file, and then only retrieve data with the Ajax call.
However, I believe it should work by calling eval() on the response - provided it is syntactically correct JavaScript code.
Just remember if you create a function the way below through ajax...
function foo()
{
console.log('foo');
}
...and execute it via eval, you'll probably get a context problem. Take this as your callback function:
function callback(result)
{
responseDiv = document.getElementById('responseDiv');
responseDiv.innerHTML = result;
scripts = responseDiv.getElementsByTagName('script');
eval(scripts[0]);
}
You'll be declaring a function inside a function, so this new function will be accessible only on that scope.
If you want to create a global function in this scenario, you could declare it this way:
window.foo = function ()
{
console.log('foo');
};
But, I also think you shouldn't be doing this...
Sorry for any mistake here...
With jQuery I would do it using getScript
Source: Stackoverflow.com